Exhaust collector conversion system and method

ABSTRACT

A system includes an exhaust collector tunnel ( 32 ) configured to mount inside an exhaust collector ( 30 ) of a gas turbine ( 12 ). The exhaust collector tunnel ( 32 ) has a tunnel wall ( 33 ) configured to extend around a turbine shaft ( 17, 19 ) of the gas turbine ( 12 ). The tunnel wall ( 33 ) has a variable diameter ( 98 ) along at least a portion of a length of the exhaust collector tunnel ( 32 ).

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority pursuant to 35 U.S.C. 119(a) of PolandApplication No. P.434311, filed Jun. 15, 2020, which application isincorporated herein by reference in its entirety.

FIELD OF THE INVENTION

The subject matter disclosed herein relates to turbine systems, and moreparticularly to systems and methods for turbine systems with an exhaustcollector.

BACKGROUND

Power generation plants, such as combined cycle power plants, oftenincorporate a gas turbine engine. The gas turbine engine combusts a fuelto generate hot combustion gases, which flow through a turbine to drivea load, e.g., an electrical generator. At high velocities andtemperatures, an exhaust gas exits the turbine and enters an exhaustcollector. Unfortunately, exhaust collectors are generally useable onlywith one type of turbine engine.

BRIEF DESCRIPTION

Certain embodiments commensurate in scope with the originally claimedsubject matter are summarized below. These embodiments are not intendedto limit the scope of the claimed subject matter, but rather theseembodiments are intended only to provide a brief summary of possibleforms of the subject matter. Indeed, the subject matter may encompass avariety of forms that may be similar to or different from theembodiments set forth below.

In a first embodiment, a system includes an exhaust collector tunnelconfigured to mount inside an exhaust collector of a gas turbine. Theexhaust collector tunnel has a tunnel wall configured to extend around aturbine shaft of the gas turbine. The tunnel wall has a variablediameter along at least a portion of a length of the exhaust collectortunnel.

In a second embodiment, a system includes an exhaust collectorconfigured to couple to a gas turbine. The exhaust collector includes anexhaust collector frame, an exhaust diffuser disposed in the exhaustcollector frame, a diverging section disposed in the exhaust collectorframe downstream from the exhaust diffuser, and an exhaust collectortunnel disposed in the exhaust collector frame between the exhaustdiffuser and the diverging section. The exhaust collector tunnel has atunnel wall configured to extend around a turbine shaft of the gasturbine. The tunnel wall has a variable diameter along at least aportion of a length of the exhaust collector tunnel.

In a third embodiment, a method includes installing an exhaust collectortunnel inside an exhaust collector of a gas turbine. The exhaustcollector tunnel has a tunnel wall configured to extend around a turbineshaft of the gas turbine. The tunnel wall has a variable diameter alongat least a portion of a length of the exhaust collector tunnel.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features, aspects, and advantages of the present subjectmatter will become better understood when the following detaileddescription is read with reference to the accompanying drawings in whichlike characters represent like parts throughout the drawings, wherein:

FIG. 1 is a diagram of an embodiment of a gas turbine power plant havingan exhaust collector assembly, which can be modified (e.g., retrofit)with a plurality of different tunnels, diffusers, seals, and mounts;

FIG. 2 is a cross-sectional view of an embodiment of the exhaustcollector assembly of FIG. 1, illustrating a retrofit kit having atunnel (e.g., constant diameter tunnel) that can be used to retrofit theexhaust collector assembly;

FIG. 3 is a partial cross-sectional view of the exhaust collectorassembly of FIG. 2, illustrating an embodiment of a turbine connectionassembly;

FIG. 4 is a partial cross-sectional view of the exhaust collectorassembly of FIG. 2, illustrating an embodiment of a diffuser connectionassembly;

FIG. 5 is a cross-sectional view of an embodiment of the exhaustcollector assembly of FIG. 1, illustrating a retrofit kit having atunnel (e.g., variable diameter tunnel) that can be used to retrofit theexhaust collector assembly;

FIG. 6 is a partial cross-sectional view of the exhaust collectorassembly of FIG. 5, illustrating an embodiment of a turbine connectionassembly;

FIG. 7 is a partial cross-sectional view of the exhaust collectorassembly of FIG. 5, illustrating an embodiment of a diffuser connectionassembly;

FIG. 8 is a cross-sectional view of an embodiment of the exhaustcollector assembly of FIG. 1, illustrating a retrofit kit having atunnel (e.g., stepped tunnel) that can be used to retrofit the exhaustcollector assembly;

FIG. 9 is flow chart of a method of removing portions of the exhaustcollector assembly in preparation of retrofitting using one of theretrofit kits of FIGS. 2-8; and

FIG. 10 is flow chart of a method of installing one of the retrofit kitsof FIGS. 2-8 to modify the exhaust collector assembly of FIG. 1.

DETAILED DESCRIPTION

One or more specific embodiments of the present subject matter will bedescribed below. In an effort to provide a concise description of theseembodiments, all features of an actual implementation may not bedescribed in the specification. It should be appreciated that in thedevelopment of any such actual implementation, as in any engineering ordesign project, numerous implementation-specific decisions must be madeto achieve the developers' specific goals, such as compliance withsystem-related and business-related constraints, which may vary from oneimplementation to another. Moreover, it should be appreciated that sucha development effort might be complex and time consuming, but wouldnevertheless be a routine undertaking of design, fabrication, andmanufacture for those of ordinary skill having the benefit of thisdisclosure.

When introducing elements of various embodiments of the present subjectmatter, the articles “a,” “an,” “the,” and “said” are intended to meanthat there are one or more of the elements. The terms “comprising,”“including,” and “having” are intended to be inclusive and mean thatthere may be additional elements other than the listed elements.

The disclosed embodiments include a retrofit kit for use with an exhaustcollector of a gas turbine engine system. The retrofit kit includes oneor more diffusers having different sizes and interfaces, a tunnelcoupled to a diverging section (e.g., a conical section, deflectorsection) of the exhaust collector and the turbine frame via acombination of a coupling structure (e.g., bolts, brackets) and one ormore enlarged seal assemblies (e.g., circumferential groove,circumferential seal segments, bolts, etc.). The tunnel may pass througha diffuser section of the gas turbine engine such that the tunnel isconcentric with the diffuser section. That is, the tunnel (e.g., bore)may be thermally insulated and coupled to an exhaust collector frame,extend into a collector chamber, pass through the exhaust diffuser, andcouple with the gas turbine engine. The tunnel may surround a linkage(e.g., shaft coupling of gas turbine and load shafts), thermallyinsulating the linkage from hot gases. The tunnel may be a retrofit oran original component of the gas turbine engine. For example, thedisclosed embodiments include a retrofit kit including an exhaustcollector tunnel that enables a particular exhaust system (e.g., anexhaust collector) designed for a larger turbine engine to be used witha different turbine engine by changing an interface between the exhaustcollector tunnel and a gas turbine frame used to couple the tunnel tothe gas turbine engine.

The retrofit kit uses one or more seal carriers to reduce leakage ofexhaust gas. The tunnel has a geometry designed to transition from thegas turbine engine to the diverging section (e.g., conical section,deflector section) of the exhaust collector. For some embodiments of thegas turbine engine, the geometry of the tunnel may be cylindrical (e.g.,a straight annular wall) from the gas turbine engine to the divergingsection. However, for other embodiments of the gas turbine engine, thegeometry of the tunnel may be variable (e.g., variable diameter annularwall) from the gas turbine engine to the diverging section. For example,the annular wall of the tunnel may gradually increase or decrease fromthe gas turbine engine to the diverging section. The annular wall of thetunnel may have a frustoconical shape, a curved annular shape, a steppedannular shape (e.g., annular wall with a plurality of steps indiameter), or a combination thereof. As a result, the retrofit kitenables exhaust collectors designed for a larger gas turbine engine tobe used on other models of gas turbine engines (e.g., smaller engines),or vice versa, without the need for complex modifications to the exhaustcollector enclosure or other package enclosures of the gas turbineengine power plant. For example, the retrofit kit may enable the tunnelto mount directly between an existing exhaust collector and gas turbineframe. Although a retrofit kit is presently contemplated for a gasturbine engine, the disclosed embodiments are not limited to a retrofitkit.

Turning now to the drawing and referring first to FIG. 1, a diagram of agas turbine engine power plant 10 is illustrated. A gas turbine engine12 (or gas turbine), for example an aeroderivative gas turbine engine,is coupled to an exhaust collector assembly 14. The diagram also depictsan electrical generator 16 coupled to the turbine engine 12 through alinkage 18 (e.g., rotary coupling or shaft coupling). The gas turbineengine 12, exhaust collector assembly 14, and electrical generator 16may be securely attached to a skid platform 20. Clean air for combustionmay be supplied by an air intake and filtration system 22. The air iscompressed in a compressor section of the gas turbine engine 12 andmixed with a liquid fuel or gas fuel, such as natural gas. The fuel-airmixture is then combusted in a combustion chamber of the gas turbineengine 12. Hot pressurized gas resulting from the combustion of thefuel-air mixture then passes through a plurality of turbine blades inthe gas turbine engine 12. The hot pressurized gas will cause theturbine blades to rotate, causing the rotation of the linkage 18. Therotation of the linkage 18 may drive a load, such as the electricalgenerator 16, as illustrated.

In one embodiment, the hot gas exits the gas turbine engine 12 in anaxial direction and enters the exhaust collector assembly 14 downstreamof the gas turbine engine 12. The gas turbine engine 12 converts aportion of the energy in the hot gas into rotary motion. However, someuseful energy may still remain in the hot exhaust gas. Accordingly, theexhaust collector assembly 14 may capture and route the hot exhaust gasfor further use, for example, by a heat recovery steam generator (HRSG).The HRSG may use the hot exhaust gas to generate steam for use in asteam generator and/or other equipment in the power plant 10. The hotgas exiting into the exhaust collector assembly 14 may be flowing athigh velocities and contain high temperatures. By using the embodimentsdescribed in more detail with respect to FIGS. 2-10 below, the exhaustcollector assembly 14 that was designed for a first gas turbine engine(e.g., a first power turbine) may be used with a second gas turbineengine (e.g., a second power turbine). The first and second gas turbineengines may different in model number, physical size, power output, andgeometry of the turbine outlet or connection with an exhaust collector.However, the disclosed embodiments address these differences by adaptingor retrofitting the exhaust collector assembly 14 for use with anydesired gas turbine engine.

FIG. 2 illustrates a perspective view of an embodiment of an exhaustcollector 30 of the gas turbine system 10, where the exhaust collector30 is coupled to a tunnel 32 (e.g., an exhaust collector tunnel or shaftcoupling tunnel). For clarity of illustration of the features of thetunnel 32, the entirety of the turbine 12, the linkage 18, the airintake and filtration system 22 of the gas turbine system 10 are notshown in FIG. 2. Components of the gas turbine engine system 10, such asthe exhaust collector 30, may be disposed in one or more frames 34. Theexhaust collector 30 is coupled to a diffuser 36, which is downstream ofthe turbine 12 relative to an inlet axis (i.e., turbine axis 38). Thediffuser 36 is configured to couple to an outer wall (e.g., definingouter boundary of the exhaust flow path) of the turbine 12, while thetunnel 32 is configured to couple to an inner wall (e.g., defining aninner boundary of the exhaust flow path) of the turbine 12.

The illustrated exhaust diffuser 36 has an annular wall 40, whichgradually increases in diameter in a downstream direction 42 of theexhaust flow from the gas turbine engine 12 toward the exhaust collector30. The annular wall 40 may be described as a diverging or expandingannular wall, which diverges away from a longitudinal axis 44 in thedownstream direction 42 of exhaust flow. The annular wall 40 may expandlinearly (e.g., frustoconical wall) and/or curvilinearly (e.g., curvedannular wall or bell shaped wall). The smaller diameter end 46 of thediffuser 36 is coupled to the gas turbine engine 12 (portion shown). Thediffuser 36 diffuses (e.g., spreads out and reduces velocity of) anaxial flow of the exhaust gas flowing from the gas turbine engine 12.The exhaust collector 30 receives the exhaust flow along the inlet axisfrom the diffuser 36 into a collector chamber 37.

The exhaust collector 30 is disposed within an exhaust collector frame34 (e.g., enclosure) which includes a right wall 48, a top wall 50, aleft wall 52, a bottom wall 54, a back wall 56, and a front wall 58. Adiverging section 60 (e.g., a diverging annular wall or diverging wall)may project axially out of the left wall 52 and into the exhaustcollector 30. The diverging section 60 may have a constant orsubstantially constant angle (e.g., deflector section or frustoconicalwall) and/or a variable angle (e.g., a curved annular wall, such as abell shape) relative to the longitudinal axis 44. For example, the anglemay be approximately 20 to 70 degrees, 30 to 60 degrees, or 40 to 50degrees. The diverging section 60 may be used, for example, to radiallydisperse some of the gas flow, such that the gas flow does not directlyimpinge against the left wall 52 in the same axial direction. Asillustrated, the diverging section 60 diverges in the downstreamdirection 42 along the longitudinal axis 44, thereby graduallyredirecting the exhaust flow from an axial direction 62 to a radialdirection 64.

The tunnel 32 may be thermally insulated and coupled to the divergingsection 60, extend into the exhaust collector 30, pass through thediffuser 36, and couple to the gas turbine engine 12 via a turbine frame66 (see FIG. 3). The thermally-insulated tunnel 32 may include anannular wall 33 having one or more walls or layers made of the same ordifferent materials. For example, the annular wall 33 may include aninner annular wall 68, an outer annular wall 70, and one or more layersof insulation 69 between the inner and outer annular walls 68 and 70.The tunnel 32 may be coaxial with the longitudinal axis 42, e.g.,approximately at the axial center of the inside hollow region of thediffuser 36. The tunnel 32 may pass through a diffuser opening 72 on oneend and couple to the turbine frame 66. The tunnel 32 may surround thelinkage 18 (e.g., shaft coupling of shafts 17 and 19), thermallyinsulating the linkage 18 from the hot gas. The shaft 17 may be coupledto the gas turbine engine 12, while the shaft 19 may be coupled to aload, e.g., the electrical generator 16.

The tunnel 32 may be removably coupled to the diverging section 60 andthe diffuser opening 72. By removing the tunnel 32, other tunnels (seeFIGS. 5 and 8) may replace the tunnel 32, which results in a changedinterface 74 between the tunnel 32 and the turbine 12. By changing theinterface 74, the various tunnels 32 enable the exhaust collector 30 tobe used with a multitude of gas turbine engines by retrofitting thediverging section 60 of the exhaust collector 30 to the gas turbineengine 12. For example, the same diverging section 60 may be used in theexhaust collector 30 for various different gas turbine engines 12, whilethe tunnel 32 varies in geometry to transition from the same divergingsection 60 to different geometries of the different gas turbine engines12. Indeed, selecting the appropriate tunnel 32 may expand the interface(e.g., larger diameter) or decrease the interface (e.g., smallerdiameter) between the tunnel 32 and the gas turbine engine 12, so thatthe particular gas turbine engine 12 is suited for use the exhaustcollector 30. Accordingly, depending on the geometry at the gas turbineengine 12 (e.g., larger or smaller diameter), the tunnel 32 may have avariety of shapes of the annular wall 33.

As discussed above, the annular wall 33 of the tunnel 32 may have aconstant diameter (e.g., cylindrical wall) or a variable diameter (e.g.,a converging or diverging annular wall) in the flow direction 42 fromthe gas turbine engine 12 to the diverging section 60. For example, avariable diameter annular wall 33 may include a linearly variableannular wall (e.g., frustoconical wall), a curvilinearly variableannular wall (e.g., a curved annular wall), or a stepwise variableannular wall (e.g., annular wall having a plurality of steps indifferent diameters). Depending on the particular application, theannular wall 33 may have any one or more of the foregoing geometries invarious combinations with one another. In the illustrated embodiment,the tunnel 32 has a substantially straight or uniform geometry (e.g.,cylindrical wall 33) with a constant or substantially constant diameter(e.g., a diameter that deviates less than one percent) and positionedcoaxial with the longitudinal axis 44. The tunnel 32 is removablycoupled to the diverging section 60 and the turbine frame 66. At thediverging section 60, a first end 76 of the tunnel 32 is secured to thediverging section 60 via a set of tunnel flanges 78 (e.g.,circumferentially spaced flanges and/or annular flanges). The tunnelflanges 78 are bolted to the diverging section 60 and used to securethese components together via a suitable number of fasteners, e.g.,threaded bolts 75. The tunnel 32 passes through the diffuser 36, and asecond end 79 of the tunnel 32 is secured to the turbine frame 66 via aturbine connection assembly 77. A partial cross-sectional view of theturbine connection assembly 77 is illustrated in FIG. 3. The turbineconnection assembly 77 may include a set of turbine frame flanges 80(e.g., circumferentially spaced flanges and/or annular flanges). Thesecond end 79 of the tunnel 32 is bolted to the turbine frame 66 andused to secure the second end 79 of the tunnel 32 to the turbine frame66. The second end 79 of the tunnel 32 may include a first seal 82(e.g., a circumferential or annular seal) that is disposed in an openingwithin a first seal groove 86 (e.g., a circumferential or annular sealgroove). The seal 82 may include one or more segments 84 (e.g.,circumferential seal segments), which are arranged circumferentiallyabout the longitudinal axis 44 to make a 360 degree structure (e.g.,annular seal). The seal 82 may uncoupled at the groove end so it maymove freely within the opening of the first seal groove 86. The seal 82may reduce the leakage of the hot exhaust gases and reduce thepossibility of the hot exhaust gases entering the tunnel 32.

The diffuser 36 is coupled to the exhaust collector frame 34 via adiffuser connection assembly 89. A partial cross-sectional view of thediffuser connection assembly 89 is illustrated in FIG. 4. The diffuserconnection assembly 89 may include a set of exhaust enclosure flanges 88(e.g., circumferentially spaced flanges and/or annular flanges). Theexhaust enclosure flanges 88 are fastened via a plurality of fasteners(e.g., threaded bolts 75) to the exhaust collector frame 34 and are usedto secure these components together. The exhaust enclosure flanges 88may include a second seal groove 90 (e.g., circumferential or annularseal groove). One or more second seal segments 92 (e.g., circumferentialseal segments), disposed along an outer surface 41 of the diffuser 36,may be fastened (e.g., via threaded bolts) into the second seal segment92 to reduce leakage of hot exhaust gases. The second seal segments 92may be disposed circumferentially around the diffuser 36 to create a 360degree structure (e.g., annular seal). The diffuser 36 may also becoupled to turbine frame 66 upstream of the exhaust enclosure flanges 88via a set of outer diffuser flanges 95 (e.g., circumferentially spacedflanges and/or annular flanges). The outer diffuser flanges 95 arefastened to an outer turbine flange connection 96 via a plurality offasteners (e.g., threaded bolts 75) to secure these components together.

As discussed above, the tunnel 32 passes through the diffuser 36. In theillustrated embodiment, the tunnel 32 and the diffuser 36 are notdirectly coupled together via radial struts, couplings, or other supportstructures. A lack of radial struts, couplings, and other supportstructures enables the tunnel 32 to be removed more readily from theexhaust collector frame 34. The tunnel's 32 relative size to thediffuser 36 may also enable the tunnel 32 to be more easily removed. Inone embodiment, a diameter 98 (e.g., inner or outer diameter) of thetunnel 32 may be any suitable size, such as between 14 to 54 inches, 20to 48 inches, 24 to 44 inches, or any specific diameter therebetween,while a diameter 100 (e.g., inner or outer diameter) of the diffuser 36may be any suitable size, such as between 34 to 136 inches, 48 to 122inches, 60 to 110 inches, or any specific diameter therebetween.

FIG. 5 is a cross-sectional view of the exhaust collector 30 of the gasturbine system 10 of FIGS. 1 and 2, wherein the exhaust collector 30 ismodified (e.g., retrofitted) with an alternate embodiment of the tunnel32. The components of the exhaust collector frame 34 and the divergingsection 60 are substantially the same as those described above withreference to FIG. 2 and thus, the discussion of these components is notrepeated. In the illustrated embodiment, the tunnel 32 has a taperedshape 102 along the annular wall 33 from the first end 76 of the tunnel32 to the second end 79 of the tunnel 32. An angle 104 of the taperedshape 102 may be approximately 2 to 40, 3 to 35, 4 to 30, or 5 to 25degrees along the annular wall 33. In certain embodiments, the angle 104may be greater than a minimum angle of 1, 2, or 3 degrees and less thana maximum angle of 10, 15, 20, 25, or 30 degrees, or any combination ofthese minimum and maximum angles. The angle 104 may be constant orsubstantially constant (e.g., deviation less than 1 degree) along aportion or an entirety of the length (e.g., at least 10, 20, 30, 40, 50,60, 70, 80, 90, or 100 percent of the length) between the first end 76and the second end 79. If the angle 104 is constant or substantiallyconstant, then the annular wall 33 of the tunnel 32 may be described asa tapered annular wall (or a tapered annular wall portion if less thanthe entire length of the annular wall 33). Alternatively oradditionally, the angle 104 may be variable (e.g., varying in acurvilinear manner by at least 2, 3, 4, 5, 6, 7, 8, 9, or 10 degrees)along a portion or an entirety of the length (e.g., at least 10, 20, 30,40, 50, 60, 70, 80, 90, or 100 percent of the length) between the firstend 76 and the second end 76. For example, if the angle 104 varies in acurvilinear manner, then the annular wall 33 of the tunnel 32 may bedescribed as a curved annular wall (or a curved annular wall portion ifless than the entire length of the annular wall 33). The annular wall 33may reduce and/or diffuse stress along the tunnel 32 by improving thecapacity of the expected high stress areas of the walls 68, 70. Thefirst end 76 of the tunnel 32 may be coupled to the diverging section60, as discussed above with reference to FIG. 2. That is, the first end76 of the tunnel 32 may be coupled to the diverging section 60 via theset of tunnel flanges 78 (e.g., circumferentially spaced flanges and/orannular flanges).

FIG. 6 is a partial cross-sectional view of an alternate embodiment ofthe turbine connection assembly 77, which may be used with the taperedtunnel 32 of FIG. 5 or the tunnels 32 illustrated in FIGS. 3 and 8. Inthe illustrated embodiment, the second end 79 of the tapered tunnel 32may be coupled to the turbine frame bracket 80 via the one or morefasteners (e.g., threaded bolts 75). The second end 79 of the tunnel 32and the turbine frame bracket 80 may form a first seal groove 86 (e.g.,annular seal groove) for receiving the seal 82 (e.g., annular seal orcircumferentially segmented seal). For example, the seal 82 may includea plurality of circumferential seal segments that are held in place inpart due to the force of the turbine frame bracket 80.

FIG. 7 is a partial cross-sectional view of an alternate embodiment ofthe diffuser connection assembly 89, which may be used with the taperedtunnel 32 of FIG. 5 or the tunnels 32 illustrated in FIGS. 3 and 8. Thediffuser connection assembly 89 may include a lip 93 that is connected(e.g., via a welded connection) to the outer surface 41 of the diffuser36. The lip 93 (e.g., annular lip) extends circumferentially around theouter surface 41 of the diffuser 36. The lip 93 also may include theseal segments 92 arranged circumferentially around the outer surface 41of the diffuser 36. The diffuser connection assembly 89 includes atleast two diffuser brackets 94 (e.g., circumferentially spaced bracketsand/or annular brackets) to create groove 90 (e.g., annular seal groove)that receives the seal segments 92. The diffuser brackets 94 may becoupled together via the fasteners, e.g., threaded bolt 75. The diffuserbrackets 94 may also be coupled to the exhaust enclosure flange 88.

Referring again to FIG. 5, the first end 76 of the tunnel 32 has adiameter 98 (e.g., inner or outer diameter) sized differently (e.g.,larger) than a diameter 106 (e.g., inner or outer diameter) of thesecond end 79 of the tunnel 32. Thus, the annular wall 33 of the tunnel32 has a variable diameter between the first and second ends 77 and 79.The tapered tunnel 32 enables a changed interface between the second end79 of the tunnel 32 and the turbine frame 66. For example, a ratio ofthe diameter 98 (e.g., inner or outer diameter) at the first end 76relative to the diameter 106 (e.g., inner or outer diameter) at thesecond end 79 is greater than 1, such as at least equal to or greaterthan 1.05, 1.1, 1.15, 1.2, 1.25, 1.3, 1.45, or 1.5. The tapered tunnel32 enables the diverging section 60 (e.g., the same diverging section asFIG. 2) to be used with a different diffuser 36 of a different gasturbine engine 12 (e.g., a low power turbine or other suitable turbineengine). For example, the diameter 106 and the angle 104 may bespecifically selected to enable a retrofit with a different gas turbineengine 12 and/or a different diffuser 36. Accordingly, a ratio of adiameter 100 (e.g., inner or outer diameter) of the diffuser 36 relativeto the diameter 106 (e.g., inner or outer diameter) at the second end 79may be equal to or greater than 1.5, 1.75, 2, 2.25, 2.5, 2.75, or 3, forexample.

In the illustrated embodiment, the diameter 98 (e.g., inner or outerdiameter) of the first end 76 of the tunnel 32 may be any suitable size,such as between 12 to 50 inches, 18 to 44 inches, 22 to 40 inches, orany specific diameter therebetween, while the diameter 106 (e.g., inneror outer diameter) of the second end 79 of the tunnel 32 may be anysuitable size, such as between 8 to 48 inches, 14 to 42 inches, 20 to 38inches, or any specific diameter therebetween. In the illustratedembodiment, the diameter 100 (e.g., inner or outer diameter) of thediffuser 36 may be any suitable size, such as between 34 to 136 inches,48 to 122 inches, 60 to 110 inches, or any specific diametertherebetween. As discussed above, the tunnel 32 and the diffuser 36 arenot directly coupled together via radial struts, couplings, or othersupport structures, thereby enabling the tunnel 32 to be removed morereadily from the exhaust collector frame 34.

FIG. 8 is a cross-sectional view of the exhaust collector 30 of the gasturbine system 10 of FIGS. 1, 2, and 5, wherein the exhaust collector 30is modified (e.g., retrofitted) with an alternate embodiment of thetunnel 32. The components of the exhaust collector frame 34 and thediverging section 60 are substantially the same as those described abovewith reference to FIGS. 2 and 5 and thus, the discussion of thesecomponents is not repeated. In the illustrated embodiment, the exhaustcollector 30 of FIG. 8 has the turbine connection assembly 77 asillustrated in FIG. 9 and the diffuser connection assembly 89 asillustrated in FIG. 10. However, in some embodiments, the exhaustcollector 30 of FIG. 8 may have the turbine connection assembly 77 asillustrated in FIG. 3 and/or the diffuser connection assembly 89 asillustrated in FIG. 4.

In the illustrated embodiment, the tunnel 32 has a step portion 108(e.g., an annular step or abrupt diameter change, such as a stepped wallportion) along the annular wall 33 between the first end 76 of thetunnel 32 and the second end 79 of the tunnel 32. The step portion 108transitions between adjacent wall portions 107 and 109 of the annularwall 33 of the tunnel 32. Although FIG. 8 illustrates only one stepportion 108, embodiments of the tunnel 32 may include any number of stepportions 108 (e.g., 1, 2, 3, 4, 5, 6, or more annular steps) betweenadjacent wall portions 107 and 109. The adjacent wall portions 107and/or 109 may be cylindrical or tapered. Each step portion 108, such asthe illustrated step portion 108, may change (e.g., reduce) the diameterof the annular wall 33 by some dimension or percentage from the wallportion 107 to the wall portion 109. For example, each step portion 108may reduce a diameter 110 (e.g., inner or outer diameter) of the annularwall 33 by at least 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, or more inches, or byat least 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, or more percent relative to thediameter of the annular wall 33 (e.g., at wall portion 107) immediatelybefore the step portion 108. In some embodiments, the step portion 108may reduce the diameter 110 to be the same as the diameter 106 at thesecond end 79, or the step portion 108 may reduce the diameter 110 suchthan the angle 104 of the wall portion 107 is less than or equal toapproximately 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 degrees. Furthermore, thestep portion 108 may have an angle 111 (e.g., an acute angle) relativeto the longitudinal axis 44, such as between 15 to 90 degrees, 20 to 75degrees, 30 to 60 degrees, or 40 to 50 degrees. In some embodiments, theangle 111 of the step portion 108 may be substantially the same as anangle 61 of the diverging section 60, wherein the angle 61 is alsomeasured relative to the longitudinal axis 44. However, the angle 111 ofthe step portion 108 may be different than the angle 61 of the divergingsection 60, such as a greater angle to more rapidly transition to thesmaller diameter 110.

Similar to the embodiment shown in FIG. 5, the first end 76 of thetunnel 32 has a larger diameter 98 (e.g., inner or outer diameter)relative to the diameter 106 (e.g., inner or outer diameter) of thesecond end 79 of the tunnel 32. Accordingly, the step portion 108enables a changed interface between the second end 79 of the tunnel 32and the frame 66. In the illustrated embodiment, the first end 76 of thetunnel 32 has a diameter 90 (e.g., inner or outer diameter) between 12to 50 inches, 18 to 44 inches, 22 to 40 inches, or any specific diametertherebetween. At the first step 108, the tunnel diameter is reduced andhas a tunnel diameter 110 between 8 to 48 inches, 14 to 42 inches, 20 to38 inches, or any specific diameter therebetween. The inner diameter 106of the second end 79 of the tunnel 32 is between 10 to 46 inches, 16 to40 inches, 22 to 36 inches, or any specific diameter therebetween. Theillustrated tunnel 32 (e.g., stepped tunnel) is disposed between thediverging section 60 and a different diffuser 36 of a different gasturbine engine 12. In the illustrated embodiment, the second diffuser 36has a diameter 100 (e.g., inner or outer diameter) which may be anysuitable size, such as between 34 to 136 inches, 48 to 122 inches, 60 to110 inches, or any specific diameter therebetween.

FIG. 9 illustrates a method 200 of removing portions (e.g., the firsttunnel 32 and the first diffuser 36) of the exhaust collector assembly14 in preparation of retrofitting using one of the retrofit kits ofFIGS. 2-8 in accordance with the embodiments disclosed herein. Themethod 200 includes disengaging (block 202) the power turbine 12 and thetunnel 32. The method 200 includes detaching (block 204) the back wall56 of the package's enclosure 30. By removing the back wall 56 of theexhaust enclosure 30, the tunnel 32 and the diffuser 36 can be removedfrom the exhaust enclosure 30. The method 200 includes uncoupling (block206) the tunnel 32 from the diverging section 60 (e.g., deflectorsection). Uncoupling the tunnel 32 may include unbolting the first end76 of the tunnel 32 from the diverging section 60 (e.g., deflectorsection). The method 200 includes disengaging the seals 82 of the tunnel32. Disengaging the seals 82 may include disassembling the turbine frame80 from the second end 79 of the tunnel 32. The method 200 includesremoving the installed tunnel 32 (block 208) from the exhaust collector30 along the axis 38. The method 200 includes uncoupling (block 210) thediffuser 36 from the turbine 12. Uncoupling the diffuser 36 may includedisassembling the diffuser brackets 94 from the exhaust enclosureflanges 88. The method includes disengaging (block 212) the diffuserseal 92. The method 200 includes removing the installed diffuser 36along the axis 38.

FIG. 10 illustrates a method 300 of installing one of the retrofit kitsof FIGS. 2-8 (e.g., installing a different replacement tunnel 32 and adifferent replacement diffuser 36 after performing the method 200 ofFIG. 9) to modify the exhaust collector assembly 14 of FIG. 1 inaccordance with the embodiments disclosed herein. The method 300 mayinclude installing (block 302) the replacement diffuser 36 into theexhaust enclosure 30. The method 300 further includes coupling (block304) the replacement diffuser 36 into place by securing the smallerdiameter end 46 of the diffuser 36 to the turbine frame 66 by boltingthe diffuser 36 to the turbine frame 66 via one or more bolt and flangeconnections or brackets. The method 300 includes engaging (block 306)the replacement seal 92 of the replacement diffuser 36. The method 300includes installing (block 308) the replacement tunnel 32. The method300 includes coupling (block 310) the first end 76 of the tunnel 32 tothe diverging section 60 (e.g., deflector section). Coupling the firstend 76 of the tunnel 32 to the diverging section 60 (e.g., deflectorsection) may include bolting the first end 76 of the tunnel 32 to one ormore tunnel flanges 78 at the diverging section 60. The method 300includes engaging (block 312) the seals 82 at the opposite second end 79of the tunnel 32. Once the tunnel 32 is installed, the method 300includes replacing (block 314) the back wall 56 of the exhaust enclosure30. The foregoing methods 200 and 300 may be used to modify (e.g.,retrofit) the exhaust collector assembly 14 to change between any of theembodiments shown in FIGS. 1-8, such that the exhaust collector assembly14 can be used with any desired gas turbine engine 12 (e.g., switchbetween different sizes, models, types, etc. having different dimensionsat the connection to the exhaust collector assembly 14).

Technical effects of the invention include the ability to use a retrofitkit including the tunnel that enables a particular exhaust system (e.g.,an exhaust collector) designed for a larger turbine engine to be usedwith a different turbine engine by changing an interface between thetunnel and a turbine frame. The retrofit kit includes one or morediffusers having different sizes and interfaces, the tunnel and one ormore seal assemblies to reduce leakage of exhaust gas. The tunnel mayhave straight, tapered, curved, stepwise, or other suitably shaped wallsto fit between the exhaust collector and the turbine frame. As a result,the retrofit kit enables exhaust collectors designed for a larger gasturbine engine to be used on other models of gas turbine engines withoutthe need for extensive modifications to the exhaust collector frame orother enclosures for various components of the gas turbine engine powerplant.

This written description uses examples to disclose the claimed subjectmatter, including the best mode, and also to enable any person skilledin the art to practice the subject matter, including making and usingany devices or systems and performing any incorporated methods. Thepatentable scope of the subject matter is defined by the claims, and mayinclude other examples that occur to those skilled in the art. Suchother examples are intended to be within the scope of the claims if theyhave structural elements that do not differ from the literal language ofthe claims, or if they include equivalent structural elements withinsubstantial differences from the literal language of the claims.

1. A system, comprising: an exhaust collector tunnel (32) configured tomount inside an exhaust collector (30) of a gas turbine (12), whereinthe exhaust collector tunnel (32) comprises a tunnel wall (33)configured to extend around a turbine shaft (17, 19) of the gas turbine(12), and the tunnel wall (33) has a variable diameter (98) along atleast a portion of a length of the exhaust collector tunnel (32).
 2. Thesystem of claim 1, wherein the variable diameter (98) is configured toenable a retrofit of the exhaust collector (30) to fit a geometry of thegas turbine (12).
 3. The system of claim 2, wherein the exhaustcollector tunnel (32) is configured to replace a different exhaustcollector tunnel (32) to enable connection of the exhaust collector (30)with the gas turbine (12), and the different exhaust collector tunnel(32) is not configured to connect with the gas turbine (12).
 4. Thesystem of claim 1, wherein the exhaust collector tunnel (32) comprises afirst end portion (79) configured to extend into an exhaust diffuser(36) and a second end portion (76) configured to couple to a divergingsection (60) of the exhaust collector (30), and the diverging section(60) is disposed downstream from the exhaust diffuser (36).
 5. Thesystem of claim 4, wherein the diverging section (60) comprises adeflector section.
 6. The system of claim 4, comprising the exhaustcollector (30) having the exhaust diffuser (36) and the divergingsection (60).
 7. The system of claim 6, comprising the gas turbine (12)configured to couple to the exhaust collector (30).
 8. The system ofclaim 1, comprising an exhaust diffuser (36), wherein the exhaustcollector tunnel (32) extends at least partially into the exhaustdiffuser (36), and the exhaust collector tunnel (32) is not directlycoupled to the exhaust diffuser (36).
 9. The system of claim 1, whereinthe variable diameter (98) comprises a tapered wall portion (102). 10.The system of claim 9, wherein the tapered wall portion (102) comprisesa substantially constant angle (104) relative to a longitudinal axis(44) of the exhaust collector tunnel (32).
 11. The system of claim 9,wherein the tapered wall portion (102) comprises a variable angle (104)relative to a longitudinal axis (44) of the exhaust collector tunnel(32).
 12. The system of claim 9, wherein the tapered wall portion (102)extends along at least 50 percent of the length of the exhaust collectortunnel (32).
 13. The system of claim 9, wherein the tapered wall portion(102) extends along at least 90 percent of the length of the exhaustcollector tunnel (32).
 14. The system of claim 1, wherein the variablediameter (98) comprises a stepped wall portion (108).
 15. A system,comprising: an exhaust collector (30) configured to couple to a gasturbine (12), wherein the exhaust collector (30) comprises: an exhaustcollector frame (34); an exhaust diffuser (36) disposed in the exhaustcollector frame (34); a diverging section (60) disposed in the exhaustcollector frame (34) downstream from the exhaust diffuser (36); and anexhaust collector tunnel (32) disposed in the exhaust collector frame(34) between the exhaust diffuser (36) and the diverging section (60),wherein the exhaust collector tunnel (32) comprises a tunnel wall (33)configured to extend around a turbine shaft (17, 19) of the gas turbine(12), and the tunnel wall (33) has a variable diameter (98) along atleast a portion of a length of the exhaust collector tunnel (32). 16.The system of claim 15, wherein the variable diameter (98) comprises atapered wall portion (102).
 17. The system of claim 16, wherein thetapered wall portion (102) comprises a substantially constant angle(104) relative to a longitudinal axis (44) of the exhaust collectortunnel (32).
 18. The system of claim 16, wherein the tapered wallportion (102) comprises a variable angle (104) relative to alongitudinal axis (44) of the exhaust collector tunnel (32).
 19. Amethod, comprising: installing an exhaust collector tunnel (32) insidean exhaust collector (30) of a gas turbine (12), wherein the exhaustcollector tunnel (32) comprises a tunnel wall (33) configured to extendaround a turbine shaft (17, 19) of the gas turbine (12), and the tunnelwall (33) has a variable diameter (98) along at least a portion of alength of the exhaust collector tunnel (32).
 20. The method of claim 19,comprising: removing a different exhaust collector tunnel (32) from theexhaust collector (30) prior to installing the exhaust collector tunnel(32), wherein the different exhaust collector tunnel (32) is configuredto fit another gas turbine (12) different from the gas turbine (12).